Novel chemistries for the replacement of methylenedianiline in composites

4,4′ Methylenedianiline (MDA) is utilized to produce high performance composites; however, MDA is a known carcinogen and liver toxin. The concerns over exposure to MDA have resulted in added safety measures that increase costs for manufacturing, driving the search for potential MDA replacements. Alternatives to MDA have not gained significant traction due to reduced performance, reduced confidence in the material, and they offer a small, if any, reduction in toxicity. In this paper, we present our work on developing structure-property-toxicity relationships of various substituted dianilines by examining the effect of molecular architecture on overall polymer performance and toxicity. Novel dianilines derived from both petroleum and biomass with different numbers and types of methyl and methoxy substituents on the aromatic ring were synthesized to eliminate toxicity and carcinogenic aspects of the resulting material while maintaining thermal and mechanical integrity. Structure-toxicity relationships indicate that multiple substituents on the aromatic ring are necessary to severely reduce the toxicity of the dianiline. Structure-property relationships show that methoxy groups reduce the glass transition temperature and thermal degradation temperature while methyl groups only slightly affect these properties.